I am looking for confirmation on the usage of top tank radiators. Many people feel the 1961 only got top tanks up to vin #1700, but I don't agree. If you look at the documentation and judging manuals you will see they had 3147516 in 1960 and these were saposed to be used up on 61's, which ran out about vin#1700. Then the factory started to use 3151116 on all 270 and 315 hp cars, for the rest of the year. The 3151116 was the same as 3147516 except it included the drain assembly. The NCRS radiator documents have errors all over the part numbers and materials page. The 3151116 top tank is listed as using a surge tank, which is wrong. The part number for 60-61 early top tank is a typo with 3747516, and several others are listed as aluminum are really brass. I have an original blue print of the 3151116. It has engineering changes being made as late as 6-61. I can't believe they would be working on a discontinued part. Anyway, anyone know of late 1961 with top tanks?
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Re: 61 top tank radiators
I have a friend who has a car built in late October that has an original top tank. It is a 315 hp. The mid December 61 that I owned until recently had the surge tank. It was a 230 or 245 automatic from the factory. -
Re: 61 top tank radiators
Tom, if I understand your permise correctly you're stating that all 61 270 & 315 HP cars were delivered with top tanks. All cars before 1700 and all 270 & 315 after. My friends 61 270 is original and has a surge tank.Comment
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Re: 61 top tank radiators
Tom:
This might not be as DIRECT as you would like, but there is a Harrison Radiator Bulletin (relating to patching aluminum radiators) 4 D 15 dated June 1962 that contains the following language:
on page 2: "B. Testing 1960 and EARLY 1961 model Radiators P/N's 3147516 and 3151116(supply tank attached to header)" (Capitalization supplied by me for emphasis)
on page 3: "C. Testing 1961 & 1962 Radiators P/N 3150916 and P/N 3151016 (supply tank attached to LEFT EXHAUST MANIFOLD of engine)" (Capitals supplied by me)
The last top tank might have continued until 6/61 strictly to be available as a warranty service replacement.
Hope this helps.Comment
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Re: 61 top tank radiators
The NCRS 1958-1960 Judging Manual is 12 years old. It contains a lot of misinformation about radiators. I'll take the responsibility for some of those errors but it was the best we could do at the time.
The 1961-62 Manual has just been revised. It's a LOT better than the 1989 published version BUT still has some errors.
Please don't misunderstand me in that I'm not knocking our Judging Manuals. They're the best things going in the Corvette hobby. They are NOT however perfect.
The engineering memo Bulletin 60-16 dated 9/60 regarding the first 1700 Corvettes has become the "bible" of every NCRS manual writer in recent memory, including myself until recently. In actuality this bulletin meant well and stated a policy for radiator use at St. Louis. The bulletin was never followed.
The new 916 with external expansion tank was the radiator for 1961 & 1962. The collection of radiators on hand at St. Louis at the start of 1961 production were used up at random regardless of whether they were copper/brass, the top tank 516, or the top tank 116. There was NO correlation with Corvette horsepower, color, or options. I have always wondered about the use of core supports, hoods, and air dams in getting rid of old inventory since top tanks, 916s, and copper/brass all have different core supports and the top tanks used a slightly different hood. It seems that with each revision of the Judging Manual, an attempt is made to reprint this useless bulletin and make all the typos and misunderstood numbers conform to a chart or table.
I feel that ANYTHING GOES during early 1961 production. That includes the earliest of 1960 top tank versions since inventory control at St. Louis is NOT understood. Maybe the very first top tank got stuck behind the incoming aluminum radiators and stayed there for years. It is true indeed that the start of 1961 production marked a "housecleaning" of radiators to conform with the "spirit" of the bulletin. Such a very early radiator would then have appeared on a 1961 Corvette.
I understand that a 116 top tank was observed on an unmolested 1961 carbureted Corvette with serial number in the 3,000 range. This does NOT surprise me.
There were four versions of the top tank. The first 516 (4-11-59) had a smooth tank surface and no sight plug. The next version sported five ribs on the top of the tank. (10-26-59). Next a sight plug was added (1-7-60). On 6-14-60 the top tank got a new part number (116) and an extension to the drain petcock. None of these aluminum radiators were painted black EXCEPT for the service replacements.
The NEW 916 radiators with the separate expansion tanks weren't painted at first either. They were produced starting 11-21-60. I would expect to see them on 1961 Corvettes starting with serial number 1700! Maybe that's where the the 1700 number comes into play. (Middle of December 1960) The inlet necks, (cast aluminum) were of a slightly different design at first from the style we have become accustomed to with the square platform boss.
Nothing in Corvettes is absolute. For every rule there are exceptions. The wise restorer and/or judge will always leave the door open for exceptions to the standard when logically explainable.
Dale PearmanComment
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P.S.
Engineering changes as late as 6/61 would have to pertain to the service replacement. I understand that these replacements were availablre into the 1962 production year.
Dale.Comment
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3151116
Dale, thanks for the comments. I too was not bashing the manuals, I was just trying to sort out the facts through the misprints. The judging manual statement on drain valves with handles facing up surprises me. I have the GM blueprint on this valve and the handle is drawn with the wings out or facing to the floor. This this correct, or being changed. tdComment
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Re: 3151116
I'm not positive about these wings but I THINK the drawing in the Judging Manual as well as the accompanying retoric is in error. Again, attempts to define absolutes are risky. In judging, either orientation would be acceptable in my opinion.
If the manufacturer were to deliver these valves with the handles installed opposite to Harrison purchase orders, (assuming they weren't made in house), what would likely have happened? Engineering would have reviewed the situation and probably would have recommended acceptance since either orientation works fine. The pressures of manufacturing scheduling and material flow would bias a decision to accept anyway.
So, who's to say with certainty that they were all the same? Maybe the repops mentioned in the JM are representative of actual history.
Dale.Comment
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